Posted on 01/29/2002 8:41:57 AM PST by RightWhale
I've often speculated such was the case. It might be fruitful for experts to investigate why Pangaea started to break up after what appears to be a long period of equilibrium. I wonder a lot, as well, about what kinds of events were involved in bringing deep plutonic rocks like Kimberlites to the surface in Africa, Siberia, Canada, Australia and other regions where diamond "pipes" are found. Could they have been the result of powerful impact events?
The theory of Pangea is interesting but I would like to hear more of how a single continent originally formed or split and reformed to a single continent again. Some of these theories move continents around to fit the "disaster d'jour".
Pangaea broke up because it had been together quite long enough and it was all a big mistake to begin with, thank you very much.
:-)
I wonder a lot, as well, about what kinds of events were involved in bringing deep plutonic rocks like Kimberlites to the surface in Africa, Siberia, Canada, Australia and other regions where diamond "pipes" are found. Could they have been the result of powerful impact events?
No. Kimberlites are diatremes, which are caused by violent, volatile-rich eruptions from the deep mantle (hence, the diamonds, which require very high pressures to crystallize). Impacts, even the very largest events, only affect the upper few kilometers of planetary crusts.
Who got the ring? Very funny response but it doesn't help much with my question.
Kimberlites are diatremes, which are caused by violent, volatile-rich eruptions from the deep mantle
Can you point me in the direction of books/info on diatreme eruptions and their cause? (I'll Google as soon as I finish this message). They seem to be very ancient events, but possibly violent enough in themselves to have influenced earth's biology if any occurred within the time life has been evolving.
I wonder if this will blow in the next 50 years.
Cheers.
As for kimberlites, there is a large, professional literature. The best reference is:
Wylie P.J. (1967) Kimberlites, in Ultramafic and Related Rocks, J. Wiley and Sons, New York, pp. 240-278.
Good luck!
Thanks very much for taking the time to post a reference. I'll definitely try to find it. Meanwhile, I've found a lot of interesting stuff on-line.
Yes, convection is pretty interesting. I melt quite a bit of gold and silver for casting jewelry and have always thought the "scum" on the surface of the melt is a fair analog for what's happening to the continents on earth's molten core (enormous differences, of course, but an analog as I said). The movement of the surface scum on molten metal seems to be related to the direction of heat application and the total amount of heat. Those two factors are probably the major ones in plate tectonics (apart from earth's rotational effects, gravitational forces, the presence of immense quantities of liquid water, etc., etc.) It still seems plausible that impacts may play some role from time to time.
And ROACHES! Oh excuse me, you Florida residents, palmetto bugs! LOL!
Then please explain the relevance of this statement from the article.---
Indeed, there are few 250 million-year-old rocks left on Earth. Most have been recycled by our planet's tectonic activity.
You need rocks to date them. You need dated rocks to rate the accuracy of the method. And you need a standard. Now you may be very precise, but very inaccurate.
This is like the association between the K/T impact and the formation of the Deccan Traps (Asia) at approximately the same time and again an impact has been indicated as a possible cause of the formation of Basalts in SE Oregon and Idaho about 17mya (starting point of Yellowstone hot spot).
Direct impacts causing volcanism "Impact Volcanism" would probably mask the impact craters in basalt and 250my can hide a lot of stuff.
A direct impact may not be necessary to cause volcanism, but the shock waves of a large impact may reinforce each other at a position globally opposite the impact site (antipode) which, taking into account the positions of the continents 65mya, seems to have happened at the K/T boundary.
Around 1980, after suffering three >6.0 magnitude earthquakes in quick succession, the USGS was very concerned that something was going on. The CO2 emissions, dome building and earthquake swarms triggered at that time are continuing.
I would say Yellowstone is a bigger danger at this time.
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Hunt for Oil Leads to Crater Linked to 'Great Dying'The team, led by geologist Luann Becker of the University of California, Santa Barbara examined undersea drilling samples taken by oil prospectors in the 1970s and '80s and since held in an Australian lab. They also studied ancient layers of Earth now exposed on land Down Under and in Antarctica. Dated to the time of the mass extinction, they found breccia, a porous rock often linked to impacts. And they uncovered tiny glass beads and material known as shocked quartz, which has been fractured in several directions. These can be indicators of the extreme heat generated when a large, high-speed extraterrestrial object slams into the planet... The findings point to the existence of a 125-mile-wide (200-kilometer) crater called Bedout off the northwest coast of Australia. The ring-like structure had previously been identified as a possible impact crater by seismic data and a map of gravity variations in the area.
by Robert Roy Britt
13 May 2004
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Well duh, so Alaska could have a State Bird...
Not just any roach can be a Palmetto Bug, only the ones bigger than 1-1/2 inches.
Ok heres what you want to know.
Ill try to keep it short. When heavy planets form initially they heat up. and are molten. than as they start to form a atmosphere the surfaced start to cold and form a think layer of mass, which over time condensates to a local point do to rotation of the planet( Pangaea) the subsurface layer( under the liquid, typically water based, forms a solid crust. This a common scenario fyi and and about 85 percent of starts have planets and about 1 in 1000 stars have some from of live. Now what happened here is that a very large meteor pinged earth like a pool ball, near what was than northern africa roughly, according to most maps, and fractured the crust like a egg shell, this is also very common occurance over such a long period of time. hence the creation of the plates, what happens that causes great extinctions in life forms is, as the fractures occur you get massive volcanic activity all at the the same time along the fractured plate boundrys, which causes a number of effectss, the 2 primary being poisonous gases and atmospheric changes in content and Temperature, which tends to crush most forms of life, much of what goes extinct depends on the type and severity of the effects and somewhat on geological locations etc etc etc you can figure the rest ,,it can actually be modeled. if your understanding/science is great enough. please forgive the bad grammer and this is a summary fyi and not complete detail..didnt fell like typing to much or editing to much :) Im tired and its late
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